... the files containing:
#slideshow .widgetcontainer widget_slideshow
#search .widgetcontainer widget_thematic_search
I used the Firefox add-on Web Developer, and "Inspect Element" on my site http://www.persnicketypubs.com/ppubs/, to locate these line items, as it appears it might put me in the neighborhood I need, so that I can alter the box "cosmetics" (padding, dimensions, etc.) containing my NextGen Gallery "Portfolio Preview" and the Search form that comes with the "Gallery" child theme.
I've keyword searched the style.css, the functions.php and a few dozen other files in both the "Gallery" and "Thematic" folders without success.